0:00:07 > 0:00:10Our planet has immense power...
0:00:13 > 0:00:18..and yet that's rarely mentioned in our history books.
0:00:20 > 0:00:22I'm here to change that.
0:00:26 > 0:00:31I'm looking at four ways the power of the planet has shaped our history.
0:00:37 > 0:00:45The deep Earth that provided the raw materials for our conquest of the planet.
0:00:47 > 0:00:52Wind...that has influenced the rise and fall of empires.
0:00:54 > 0:00:56Water.
0:00:56 > 0:00:58Look at that!
0:00:58 > 0:01:03Our struggle to control it has defined the character of civilisations.
0:01:05 > 0:01:09But this week I'm looking at fire.
0:01:09 > 0:01:11It's deadly,
0:01:11 > 0:01:16yet it's also the driving force behind human progress.
0:01:20 > 0:01:24But our dependence on fire has meant that events deep in the Earth's past
0:01:24 > 0:01:27have changed the course of history.
0:01:55 > 0:01:57The vibrate is a low-air alarm.
0:01:57 > 0:02:01It'll let you know when you've got a quarter of a tank of oxygen.
0:02:01 > 0:02:04- When you hear that, you need to get out.- Get out. OK.
0:02:04 > 0:02:08I'm preparing to undergo an experience that,
0:02:08 > 0:02:10on the face of it, is absolutely terrifying.
0:02:10 > 0:02:12AIR HISSES
0:02:12 > 0:02:16These stickers are to measure the temperature it reaches inside the suit.
0:02:16 > 0:02:19These will tell you how hot you're actually getting inside the suit.
0:02:19 > 0:02:22- So how hot does it go up to? - 130 degrees Fahrenheit.
0:02:24 > 0:02:26- That goes over your head.- Mm-hm.
0:02:29 > 0:02:31OK. I'm fine.
0:02:33 > 0:02:36My suit is eight layers thick,
0:02:36 > 0:02:40its visor specially tempered, gold-plated glass.
0:02:43 > 0:02:45And I've got my own air supply.
0:02:47 > 0:02:51This is what it takes to survive just a few seconds...
0:02:51 > 0:02:53HISSING
0:02:53 > 0:02:55..inside the heart of a fire.
0:02:57 > 0:02:59FLAMES ROAR AND CRACKLE
0:03:18 > 0:03:24The temperature around me is 1,600 degrees Celsius.
0:03:36 > 0:03:39For all its danger, fire is compelling -
0:03:39 > 0:03:41almost hypnotic.
0:03:54 > 0:03:55Oh, my gosh!
0:03:55 > 0:03:59- HIS BREATHING HISSES - Argh! Argh!
0:04:01 > 0:04:04MAN: Get his gloves. Get his gloves off.
0:04:04 > 0:04:09- MAN: Come on out. Go on! Go on! - Argh! Oh!
0:04:17 > 0:04:19That was scary, right at the end.
0:04:19 > 0:04:21- That was scary. - INAUDIBLE QUESTION
0:04:21 > 0:04:25No, no, no. I feel my arms burning, though. Ha-hargh!
0:04:25 > 0:04:27I'll move them around.
0:04:27 > 0:04:29Ah! That...
0:04:30 > 0:04:32..that is not a place where humans should be.
0:04:32 > 0:04:37But when you're going through and you see the flames licking up in front of you,
0:04:37 > 0:04:41just the raw energy of it is absolutely entrancing.
0:04:41 > 0:04:42But I'm burning.
0:04:42 > 0:04:46I mean, actually, my elbow, my hand... Argh-ha-ha!
0:04:46 > 0:04:47..is burning.
0:04:47 > 0:04:49I think I should get this off, actually.
0:04:55 > 0:04:58The paradox of fire is that it's lethal,
0:04:58 > 0:05:02and yet we depend on it completely.
0:05:03 > 0:05:06Fire generates our electricity.
0:05:11 > 0:05:13It drives our machines.
0:05:15 > 0:05:17We use it every day.
0:05:23 > 0:05:26But the history of our relationship with fire
0:05:26 > 0:05:29reveals how the Earth has exerted enormous power
0:05:29 > 0:05:32over the fate of peoples and nations.
0:05:43 > 0:05:48It's strange to think that for 90% of Earth's history,
0:05:48 > 0:05:50there simply was no fire.
0:05:53 > 0:05:57Ours was a barren planet of dust and rock.
0:05:57 > 0:06:00There was nothing to burn.
0:06:00 > 0:06:02Not until relatively recently,
0:06:02 > 0:06:05about 400 million years ago,
0:06:05 > 0:06:08did fire first appear.
0:06:13 > 0:06:15The key to this transformation...
0:06:16 > 0:06:17..vegetation.
0:06:19 > 0:06:22The first land plants had just appeared...
0:06:26 > 0:06:29..and they provided fuel for fire.
0:06:32 > 0:06:34But plants did something else as well.
0:06:34 > 0:06:36Every kid likes to climb trees,
0:06:36 > 0:06:39and the great thing about being grown up is the trees...
0:06:39 > 0:06:43they just get bigger, and the ways to get up them just get fancier.
0:06:46 > 0:06:51Vegetation supplied a second crucial ingredient for fire.
0:06:51 > 0:06:53HE GRUNTS
0:06:53 > 0:06:56You can see how up here in the forest canopy.
0:07:00 > 0:07:05Going on all around me is a chemical reaction - photosynthesis.
0:07:05 > 0:07:07It's happening in here, in the leaves.
0:07:07 > 0:07:11And what the photosynthesis is producing as a waste product
0:07:11 > 0:07:14is an essential ingredient for fire...
0:07:14 > 0:07:15oxygen.
0:07:19 > 0:07:25Flames cannot burn unless at least 13% of the atmosphere is oxygen.
0:07:26 > 0:07:30But the Earth's early atmosphere had almost none.
0:07:37 > 0:07:42Photosynthesising plants used sunlight to convert carbon dioxide into energy...
0:07:45 > 0:07:48..and in the process released oxygen.
0:07:50 > 0:07:53By around 400 million years ago,
0:07:53 > 0:07:57this process had raised the level of oxygen in the atmosphere
0:07:57 > 0:07:59to that critical 13%.
0:08:06 > 0:08:10Now there was only one more thing needed for fire to start.
0:08:13 > 0:08:15THUNDER CRASHES
0:08:15 > 0:08:16A spark.
0:08:20 > 0:08:24Starting fire was actually the easy bit.
0:08:24 > 0:08:26Lightning storms have raged on Earth
0:08:26 > 0:08:28for almost its entire history.
0:08:30 > 0:08:3430,000 bolts of lightning hit the ground every hour.
0:08:36 > 0:08:39THUNDER RUMBLES AND CRASHES
0:08:43 > 0:08:45CRACKLING AND ROARING
0:08:57 > 0:08:59For hundreds of millions of years,
0:08:59 > 0:09:03wildfires were controlled only by the forces of nature.
0:09:05 > 0:09:07They started spontaneously,
0:09:07 > 0:09:09spread freely...
0:09:17 > 0:09:21..and only stopped when they ran out of fuel
0:09:21 > 0:09:22or the rains came.
0:09:30 > 0:09:33But then something changed.
0:09:37 > 0:09:39We came along.
0:09:42 > 0:09:45Around 1.5 million years ago,
0:09:45 > 0:09:48early humans learnt how to control fire.
0:09:54 > 0:09:57Our distant ancestors probably first captured fire
0:09:57 > 0:10:02by grabbing a burning stick from a wildfire and keeping it nourished,
0:10:02 > 0:10:04fanning the flames to keep it alight.
0:10:10 > 0:10:14It was the beginning of a relationship that would transform the planet...
0:10:14 > 0:10:16and us.
0:10:24 > 0:10:28In that sense, fire is the human signature.
0:10:31 > 0:10:35It gave us immense power over our world.
0:10:45 > 0:10:49Cooking greatly expanded the range of foods available to us.
0:10:52 > 0:10:55It gave us warmth and light...
0:10:57 > 0:10:59..and protection against hungry predators.
0:11:01 > 0:11:04It allowed us to quickly clear large areas of land.
0:11:11 > 0:11:15Fire was the weapon that began our conquest of the planet.
0:11:30 > 0:11:32Fire was so central to our survival,
0:11:32 > 0:11:36perhaps it's no surprise that it was worshipped by some early civilisations.
0:11:40 > 0:11:45In the Middle East, one of the oldest religions in the world, Zoroastrianism,
0:11:45 > 0:11:48grew up around the worship of fire.
0:11:51 > 0:11:55For the Zoroastrians, the flame itself was sacred.
0:11:57 > 0:12:00Humans have always been drawn to fire.
0:12:00 > 0:12:05Flames have long been a symbol of a spirit far greater than ourselves -
0:12:05 > 0:12:07almost a divine presence.
0:12:12 > 0:12:15To this day, the eternal flame is still a potent symbol
0:12:15 > 0:12:18for the world's great religions.
0:12:29 > 0:12:35But the greatest landmark in our use of fire came about 6,000 years ago.
0:12:39 > 0:12:43The breakthrough centred on an extraordinary element - carbon.
0:12:47 > 0:12:50This is carbon in its purest form...
0:12:52 > 0:12:54..diamond.
0:12:59 > 0:13:02This particular stone is 25 carats
0:13:02 > 0:13:07and apparently it's worth £3.3 million.
0:13:07 > 0:13:10It's absolutely beautiful.
0:13:14 > 0:13:17Diamonds are made under extreme pressures and temperatures
0:13:17 > 0:13:18deep in the Earth.
0:13:24 > 0:13:27I've always loved the idea that the ultimate in glitz
0:13:27 > 0:13:32was to adorn ourselves in tiny pieces of the Earth's interior.
0:13:32 > 0:13:34Geological bling.
0:13:38 > 0:13:43But there are other forms of carbon that are far more valuable to us than this...
0:13:45 > 0:13:50..because carbon is the basis for all life on Earth.
0:13:56 > 0:13:59And it's the key ingredient in fire.
0:14:05 > 0:14:09And once again, it depends on photosynthesis.
0:14:11 > 0:14:13Plants use the sun's energy
0:14:13 > 0:14:15to extract carbon from carbon dioxide in the atmosphere,
0:14:15 > 0:14:18and use it to create their living tissue.
0:14:20 > 0:14:22It is this carbon that burns in a fire,
0:14:22 > 0:14:27releasing the energy that originally came from the sun as heat.
0:14:31 > 0:14:35The more carbon-rich a fuel is, the more heat it produces.
0:14:40 > 0:14:45Normal wood fires burn at about 700 degrees Celsius.
0:14:45 > 0:14:51But 6,000 years ago, our ancestors discovered the trick of burning wood
0:14:51 > 0:14:53in a low-oxygen environment.
0:14:55 > 0:14:57It only partially burns,
0:14:57 > 0:15:01but in doing so it creates a much purer, carbon-rich fuel...
0:15:03 > 0:15:04..charcoal.
0:15:08 > 0:15:13And that can burn at 1,100 degrees Celsius...
0:15:17 > 0:15:21..hot enough to melt metal out of rock.
0:15:22 > 0:15:27The invention of metal smelting, culminating in the use of iron,
0:15:27 > 0:15:31was one of the most critical turning points in human history.
0:15:31 > 0:15:34The age of metals had begun.
0:15:34 > 0:15:38HISSING
0:15:40 > 0:15:42CLANG!
0:15:44 > 0:15:46Our mastery of metal gave us tools...
0:15:50 > 0:15:52..money
0:15:52 > 0:15:54and weapons.
0:15:57 > 0:16:01It was the foundation on which human progress was built.
0:16:07 > 0:16:10So much so that by the Middle Ages,
0:16:10 > 0:16:14the production of charcoal for iron smelting was a major industry.
0:16:19 > 0:16:21But there was an inevitable problem.
0:16:24 > 0:16:27People began to run out of wood.
0:16:28 > 0:16:32CRACKING, SPLINTERING AND RUSTLING
0:16:33 > 0:16:35In prehistoric times,
0:16:35 > 0:16:40Britain had been almost completely covered in forest,
0:16:40 > 0:16:43but by the end of the 16th century,
0:16:43 > 0:16:4690% of the ancient woodland had gone.
0:16:46 > 0:16:49In London, which was growing fast,
0:16:49 > 0:16:54the shortage of accessible wood meant that the price rocketed.
0:16:59 > 0:17:03Around the growing cities of Europe and Asia,
0:17:03 > 0:17:05similar fuel shortages developed.
0:17:05 > 0:17:09In fact, the end of the 16th century
0:17:09 > 0:17:13was the world's first great energy crisis.
0:17:15 > 0:17:18In many societies, the demand for energy
0:17:18 > 0:17:22had reached the limits of what photosynthesis could provide.
0:17:26 > 0:17:29A new source of carbon was needed.
0:17:31 > 0:17:34And the planet had a solution.
0:17:41 > 0:17:46The answer to the energy shortage started out in cold, wet places...
0:17:49 > 0:17:54..like here in Oregon, in the western United States.
0:17:58 > 0:18:00This looks like a perfectly ordinary -
0:18:00 > 0:18:04if very beautiful - lake, but these waters hold a secret.
0:18:04 > 0:18:08Because down there is a lost world...and a very cold one.
0:18:16 > 0:18:20Melting glaciers keep the water clear.
0:18:27 > 0:18:31Ghostly shapes appear in the distance...
0:18:32 > 0:18:34..standing like sentinels.
0:18:36 > 0:18:38But this is not their natural home.
0:18:41 > 0:18:43These are 3,000-year-old tree trunks...
0:18:45 > 0:18:47..the remains of a drowned forest.
0:18:59 > 0:19:04They were submerged when lava from a nearby volcano dammed this valley
0:19:04 > 0:19:06and created the lake.
0:19:07 > 0:19:12These trees are completely waterlogged, but they're actually
0:19:12 > 0:19:16the crucial first stage in an extraordinary transformation.
0:19:16 > 0:19:18BREATHING HISSES
0:19:24 > 0:19:30Because the trees are under water, there is no oxygen to help rot them away.
0:19:31 > 0:19:36Instead, they're preserved, and eventually buried in mud
0:19:36 > 0:19:37at the bottom of the lake...
0:19:40 > 0:19:43..the start of a long transformation which turns wood
0:19:43 > 0:19:45into something very different.
0:19:59 > 0:20:01Oh!
0:20:01 > 0:20:03That was incredible.
0:20:03 > 0:20:05- It's absolutely freezing, though. - HE SNIFFS
0:20:05 > 0:20:08The thing is, today, there are precious few places
0:20:08 > 0:20:12where whole forests die and get preserved,
0:20:12 > 0:20:17but 300 million years ago, this was happening right across the globe.
0:20:18 > 0:20:20It was just a lot warmer then!
0:20:29 > 0:20:34300 million years ago, trees dominated the planet.
0:20:34 > 0:20:38Many of these forests were in lowland swamps.
0:20:44 > 0:20:48So when the trees died, they fell into the water.
0:20:48 > 0:20:52In fact, so many carbon-rich trees were buried
0:20:52 > 0:20:55that this period in the Earth's history
0:20:55 > 0:20:58is known as the Carboniferous -
0:20:58 > 0:20:59the Age of Carbon.
0:21:04 > 0:21:07Eventually, these drowned trees would be squeezed and cooked
0:21:07 > 0:21:12deep inside the Earth and turned into something new and different.
0:21:17 > 0:21:18Coal.
0:21:21 > 0:21:25Coal was to change our relationship with fire in a fundamental way.
0:21:28 > 0:21:33Instead of burning carbon from the present, coal gave us access
0:21:33 > 0:21:38to a huge new source of carbon from the Earth's past.
0:21:38 > 0:21:43Coal was, in essence, an immense store of fossilised sunshine.
0:21:48 > 0:21:51But coal wasn't evenly distributed across the Earth,
0:21:51 > 0:21:55and this meant that from the 17th century onwards,
0:21:55 > 0:22:01the planet began to play a new and crucial role in human history.
0:22:01 > 0:22:06The first place to benefit was a small, north-European island...
0:22:06 > 0:22:08Britain.
0:22:09 > 0:22:11Britain was lucky.
0:22:11 > 0:22:13It had an abundance of coal,
0:22:13 > 0:22:16much of which could be easily collected from the surface.
0:22:24 > 0:22:27From the beginning of the 17th century,
0:22:27 > 0:22:31burning coal began to replace wood in homes and workshops.
0:22:33 > 0:22:36It was the beginning of a transition
0:22:36 > 0:22:40that would end up changing Britain and the world.
0:22:42 > 0:22:47To see how, I'm heading to the Forest of Dean, in Gloucestershire.
0:22:52 > 0:22:55It didn't take long for all that easy-to-get-at coal to be used up,
0:22:55 > 0:22:58so the miners were forced to tunnel into the Earth,
0:22:58 > 0:23:01chasing the coal seams underground,
0:23:01 > 0:23:04and down there they had a problem.
0:23:04 > 0:23:07But it was a problem which, it turned out,
0:23:07 > 0:23:10would unleash the Industrial Revolution.
0:23:20 > 0:23:23In the process, mining condemned millions
0:23:23 > 0:23:26to a dusty, dirty, existence as men and even children
0:23:26 > 0:23:29were sent underground.
0:23:31 > 0:23:32This mine is the nearest I can get
0:23:32 > 0:23:36to experiencing what early coal mining was like.
0:23:41 > 0:23:46It's owned by Robin Morgan, who's spent all his life mining.
0:23:49 > 0:23:51Is it falling down?
0:23:51 > 0:23:54No, I'm just putting this one back up. This is a new one I'm putting in here.
0:23:54 > 0:23:56So there we go.
0:23:56 > 0:24:00That's right - drop him down there in that hole, like that.
0:24:00 > 0:24:02The first mine I ever went down,
0:24:02 > 0:24:04- I was only 13 years of age.- Oh!
0:24:04 > 0:24:06My two brothers had their own mine.
0:24:06 > 0:24:09They used to drop me down a shaft 100 foot deep
0:24:09 > 0:24:12in a 40-gallon drum with two hooks in the side
0:24:12 > 0:24:14on a hand winch.
0:24:14 > 0:24:17So where's the coal? That's what I'm looking forward to seeing.
0:24:17 > 0:24:19Well, the coal seam is actually on in there.
0:24:19 > 0:24:21- I can take you on into the seam. - Yeah, please.
0:24:23 > 0:24:26- Keep your head down here.- Yeah, OK.
0:24:31 > 0:24:35Just like the early miners, Robin hacks out the coal by hand.
0:24:41 > 0:24:43Robin, do you think I could have a go?
0:24:43 > 0:24:46You can have a go, by all means, Iain. But there's not much room up here.
0:24:46 > 0:24:47All right.
0:24:58 > 0:25:00PANTS WITH EFFORT
0:25:00 > 0:25:02Ah, dear, dear!
0:25:03 > 0:25:04I thought coal was supposed to be soft!
0:25:04 > 0:25:06Swing the pick instead of just tapping it.
0:25:06 > 0:25:08You've got to pull the pick right back
0:25:08 > 0:25:13and swing it right into those two-inch layers, and they will prise off there.
0:25:13 > 0:25:14Oh!
0:25:14 > 0:25:17My arms hurt. How do you do it, Robin?
0:25:17 > 0:25:19You get used to it over the years, you know.
0:25:19 > 0:25:22I mean to say, you've only been up there five minutes.
0:25:22 > 0:25:25- LAUGHING:- I know! I have!
0:25:25 > 0:25:28- You will gradually get used to it. - And you've been... - HE SPITS
0:25:28 > 0:25:31I like rocks all right, but...
0:25:31 > 0:25:35spending 12 hours a day smashing lumps out of them...
0:25:35 > 0:25:38- Well, that coal isn't as hard as rocks.- No.
0:25:41 > 0:25:44As you are performing at the moment, I definitely wouldn't give you a job,
0:25:44 > 0:25:47because the rate you're getting that off, you would not survive.
0:25:51 > 0:25:53But in the 17th and 18th centuries,
0:25:53 > 0:25:56the problem for Britain's miners
0:25:56 > 0:26:00was more fundamental than a lack of muscle power.
0:26:01 > 0:26:04The trouble was, the deeper they tunnelled,
0:26:04 > 0:26:08the more likely they were to encounter a major obstacle.
0:26:12 > 0:26:15Water, and plenty of it.
0:26:15 > 0:26:19300 years ago, when miners first followed the coal seams underground,
0:26:19 > 0:26:22this was a problem they faced,
0:26:22 > 0:26:26and solving this problem was the key to our industrial transformation.
0:26:33 > 0:26:38Once the miners got down to the water table, their tunnels flooded
0:26:38 > 0:26:41and the coal became inaccessible.
0:26:41 > 0:26:45It was impossible to pump the water out by hand.
0:26:45 > 0:26:48A technological solution was desperately needed...
0:26:51 > 0:26:56..and in the early 18th century, engineers came up with one.
0:26:57 > 0:27:00The steam engine.
0:27:00 > 0:27:05It was designed specifically to pump water out of mines,
0:27:05 > 0:27:08but it soon found other uses.
0:27:11 > 0:27:16Within decades, the combined power of steam and coal became the force
0:27:16 > 0:27:19behind an extraordinary, integrated economy.
0:27:19 > 0:27:21WHISTLE HOOTS
0:27:23 > 0:27:26Coal fuelled the blast furnaces which smelted steel.
0:27:29 > 0:27:32The steel was turned into trains and ships,
0:27:32 > 0:27:38powered by steam engines of course, which in turn burnt more coal.
0:27:42 > 0:27:46Today, we know this transformation in our use of fire
0:27:46 > 0:27:49as the Industrial Revolution.
0:27:57 > 0:28:00You know, being down here really focuses your mind.
0:28:00 > 0:28:03Britain owes a tremendous amount
0:28:03 > 0:28:08to that distant geological age when trees ruled the world.
0:28:08 > 0:28:10Think of the Industrial Revolution
0:28:10 > 0:28:14as the rise of carboniferous capitalism.
0:28:20 > 0:28:23But the planet was fickle with its favours.
0:28:25 > 0:28:28Britain was given huge reserves of coal
0:28:28 > 0:28:31and the geography to exploit it.
0:28:31 > 0:28:34Not everywhere was so lucky.
0:28:41 > 0:28:42There was another country
0:28:42 > 0:28:46blessed by the planet with huge reserves of coal.
0:28:47 > 0:28:48In the 17th century,
0:28:48 > 0:28:53it too was poised on the edge of an industrial revolution,
0:28:53 > 0:28:56but its story played out rather differently.
0:28:59 > 0:29:01That country
0:29:01 > 0:29:03was China.
0:29:05 > 0:29:10By this time, China had been moulded into a vast empire.
0:29:10 > 0:29:13It was rich and technologically advanced.
0:29:16 > 0:29:20China seemed perfectly positioned to exploit its coal reserves.
0:29:25 > 0:29:27There was one problem.
0:29:28 > 0:29:31China's coal reserves may have been massive,
0:29:31 > 0:29:34but they were a long way from the country's cities on the coast.
0:29:36 > 0:29:39However, running straight from the coalfields to the sea
0:29:39 > 0:29:42was the mighty Yellow River.
0:29:45 > 0:29:46So, in theory,
0:29:46 > 0:29:51transporting the coal to the market should have been possible.
0:29:57 > 0:30:01This is Qikou, a beautiful old town on the Yellow River.
0:30:02 > 0:30:06It's right in the heart of coal country.
0:30:09 > 0:30:13If coal was to be carried downstream to the coast,
0:30:13 > 0:30:15it would have to pass through here.
0:30:24 > 0:30:27Hello. How are you?
0:30:27 > 0:30:33Mr Li is 76 years old, and he's been navigating these waters since he was 11.
0:30:33 > 0:30:36His son runs a local ferry service.
0:30:39 > 0:30:42The water looks very calm.
0:30:42 > 0:30:43Very still - the water.
0:30:46 > 0:30:47Cos I get seasick.
0:30:47 > 0:30:49Can I get on? OK.
0:30:52 > 0:30:55The Li family are going to take me down the river
0:30:55 > 0:31:00in a traditional, flat-bottomed boat - a design used for generations.
0:31:03 > 0:31:05This is the route
0:31:05 > 0:31:08that coal from China's coalfields would have had to travel.
0:31:11 > 0:31:15It's like a nice, relaxing row down the Thames.
0:31:21 > 0:31:25But just downstream from Qikou is an obstacle.
0:31:32 > 0:31:37Mr Li and his friends, who boast an average age of 75,
0:31:37 > 0:31:40are the last people who know how to ride these rapids.
0:31:46 > 0:31:47SCRAPING
0:31:49 > 0:31:52These rapids are only here because the channel of the Yellow River
0:31:52 > 0:31:57gets constricted between these boulders over here and this hard rock here.
0:31:57 > 0:32:00It's literally caught between a rock and a hard place.
0:32:00 > 0:32:02It means it's really choppy.
0:32:08 > 0:32:12And it would be even harder to get through if we were laden down with coal.
0:32:20 > 0:32:22MAN SHOUTS
0:32:25 > 0:32:29Well, we made it! Just a couple of hairy moments, but...
0:32:29 > 0:32:32Mind you, it wasn't the worst set of rapids in the world,
0:32:32 > 0:32:37but it makes you realise that if you're taking a bulky cargo like coal down here,
0:32:37 > 0:32:42then either it or us are going to end up in the drink, at the bottom of the river.
0:32:44 > 0:32:46This is only the start.
0:32:46 > 0:32:49Downstream, there are many more rapids.
0:32:50 > 0:32:53MAN SHOUTS
0:32:54 > 0:32:58And just to add to the difficulties, the only way to get the boat
0:32:58 > 0:33:02back upriver is sheer manpower.
0:33:04 > 0:33:06What these rapids meant was
0:33:06 > 0:33:09that you could transport goods downstream as far as Qikou over there,
0:33:09 > 0:33:12but it was impossible to take it further.
0:33:12 > 0:33:16For cargo boats, these rapids were the end of the line.
0:33:20 > 0:33:25So the only way to get the coal to market was to carry it overland to the coast...
0:33:26 > 0:33:29..1,000 kilometres away.
0:33:30 > 0:33:35But its price doubled every 40 kilometres.
0:33:37 > 0:33:39The geography of the Yellow River ensured
0:33:39 > 0:33:45that coal could never be shipped directly to the big coastal markets,
0:33:45 > 0:33:48and that meant that the empire was effectively cut off
0:33:48 > 0:33:52from the vast reserves that could have completely transformed it.
0:33:57 > 0:34:00The British invented the steam engine to overcome
0:34:00 > 0:34:02the barrier posed by flooded mines.
0:34:04 > 0:34:08But the Chinese failed to find a similar solution
0:34:08 > 0:34:10to their geographical problems.
0:34:10 > 0:34:12It was one of those moments
0:34:12 > 0:34:14when human factors interacted
0:34:14 > 0:34:17with the opportunities the planet had to offer.
0:34:21 > 0:34:24While Britain was forging an industrial revolution,
0:34:24 > 0:34:30the Chinese were building these enormous gardens at Chengde.
0:34:31 > 0:34:35They were designed to celebrate the size and diversity of the empire.
0:34:38 > 0:34:41There was a miniature replica of the Yellow River...
0:34:43 > 0:34:46..a smaller version of the Great Wall...
0:34:46 > 0:34:51and even a copy of the Dalai Lama's palace in Tibet.
0:34:51 > 0:34:55These gardens symbolised China's preoccupation
0:34:55 > 0:34:57with managing its vast territory.
0:35:00 > 0:35:02It was such a high priority
0:35:02 > 0:35:06that rather than focusing on technological innovation,
0:35:06 > 0:35:11the brightest minds were sucked into running the empire.
0:35:16 > 0:35:19Not until the middle of the 20th century
0:35:19 > 0:35:24did China build extensive road and rail systems into its heartland
0:35:24 > 0:35:27and start its own industrial revolution.
0:35:29 > 0:35:35Ironically, China is now the biggest user and producer of coal in the world.
0:35:46 > 0:35:49China's rulers might not have found a way
0:35:49 > 0:35:54to solve their fuel crisis 300 years ago, but its people had a go.
0:35:54 > 0:36:01They came up with a brilliant invention, which today is known across the world.
0:36:01 > 0:36:05Until the 16th century, Chinese cuisine was renowned
0:36:05 > 0:36:09for its delicious stews, which took loads of time and loads of wood to cook.
0:36:09 > 0:36:12So in an era of growing wood shortage,
0:36:12 > 0:36:15a radical new approach was needed, and this was it -
0:36:15 > 0:36:17the wok.
0:36:18 > 0:36:21It's funny to think that a crippling wood famine gave us
0:36:21 > 0:36:26one of the most famous cuisines in the world - the Chinese stir-fry.
0:36:37 > 0:36:40The story of coal shows how the planet
0:36:40 > 0:36:43played a crucial role in transforming the fate of nations
0:36:43 > 0:36:46at the time of the Industrial Revolution.
0:36:50 > 0:36:54It turned fire into the energy that fuelled human progress.
0:36:56 > 0:36:59And yet that was only the beginning.
0:37:00 > 0:37:03Today, the planet's stores of ancient carbon
0:37:03 > 0:37:05have an even greater impact on our world.
0:37:10 > 0:37:14That impact hinges on another type of buried carbon.
0:37:18 > 0:37:20To see how it's formed,
0:37:20 > 0:37:24I've come to an amazing cave on an island off southern Iran.
0:37:27 > 0:37:30BANGING AND MUFFLED SPEECH
0:37:31 > 0:37:34- MAN: Do this one up nice and tight. - Cheers.
0:37:36 > 0:37:37- Is it straight down?- Yeah.
0:37:37 > 0:37:40There's a little bit of a lip and then it goes straight down,
0:37:40 > 0:37:43and then it opens out wide and you just drop into space.
0:37:43 > 0:37:46The last drop, 10-15 metres, you're in space.
0:37:48 > 0:37:51I just looked. Oh, my God!
0:37:53 > 0:37:58I have to abseil 50 metres to enter the cave system.
0:37:58 > 0:38:01Inside is evidence that reveals
0:38:01 > 0:38:05where this other store of ancient carbon comes from and how it's made.
0:38:17 > 0:38:19That is just plain weird.
0:38:19 > 0:38:20Look at those colours!
0:38:26 > 0:38:30I'm heading for some caverns that are even deeper underground.
0:38:35 > 0:38:37PANTING
0:38:39 > 0:38:40Phew!
0:38:40 > 0:38:42GRUNTS
0:38:50 > 0:38:51Oh!
0:38:51 > 0:38:54This...has got to be the toughest
0:38:54 > 0:38:57and scariest cave climb I've ever done.
0:38:57 > 0:39:01There's 100 metres of solid rock above me,
0:39:01 > 0:39:03but it's going to be worth it,
0:39:03 > 0:39:08because ahead is one of the most unusual cave systems in the world.
0:39:12 > 0:39:14Most caves are made from solid rock.
0:39:16 > 0:39:18This cavern is different.
0:39:24 > 0:39:26Oh, wow, look at these!
0:39:26 > 0:39:29These are stalactites.
0:39:30 > 0:39:32They're the weirdest ones I've ever seen.
0:39:32 > 0:39:35Normally, stalactites are made of limestone
0:39:35 > 0:39:38and they drip vertically down, but these,
0:39:38 > 0:39:40if you look at them closely,
0:39:40 > 0:39:43they're made of small crystals that twist and turn.
0:39:46 > 0:39:49You can check what they're made of really easily. You just need to lick them.
0:39:51 > 0:39:53Wow! Yeah... salt.
0:40:16 > 0:40:21Written in the roof is a clue to where the salt came from.
0:40:24 > 0:40:27This magnificent, striped banding is a real giveaway clue.
0:40:27 > 0:40:32The layers are formed when seawater evaporates away,
0:40:32 > 0:40:35leaving behind a thin residue of salt crystal.
0:40:35 > 0:40:37This is all evidence that the salt rock
0:40:37 > 0:40:41was originally laid down in an ocean that dried up.
0:40:56 > 0:41:01To create so much salt, you need to evaporate an awful lot of seawater.
0:41:02 > 0:41:06Usually, this happens in shallow seas
0:41:06 > 0:41:09which get cut off from the rest of an ocean.
0:41:09 > 0:41:14Seawater then evaporates, leaving behind a thick layer of salt.
0:41:16 > 0:41:19But it's not only salt that gets left behind
0:41:19 > 0:41:21when an ocean evaporates.
0:41:25 > 0:41:29Shallow seas are the most biologically productive part of the ocean.
0:41:29 > 0:41:31They're teeming with life...
0:41:32 > 0:41:34..all made from carbon.
0:41:42 > 0:41:47When marine creatures die, their skeletons build up on the sea floor.
0:41:48 > 0:41:51Over millions of years, these skeletons are transformed
0:41:51 > 0:41:58into a sludge of carbon and buried under sediment and layers of salt.
0:42:01 > 0:42:05One of the best places to see what that sludge ends up looking like...
0:42:06 > 0:42:10..is in the republic of Azerbaijan.
0:42:17 > 0:42:19Here they call it naftalan.
0:42:24 > 0:42:28It's been used as a health treatment for thousands of years,
0:42:28 > 0:42:32hailed as a cure for everything from rheumatism to baldness.
0:42:45 > 0:42:46Look at that!
0:42:46 > 0:42:48That looks disgusting!
0:42:49 > 0:42:52GURGLING
0:42:52 > 0:42:54It's said that 4,000 years ago,
0:42:54 > 0:42:58the Babylonians mixed this stuff with beer and drank it as a medicine.
0:43:00 > 0:43:05But there is another way to enjoy its healing properties.
0:43:12 > 0:43:13Ah...
0:43:13 > 0:43:17Ugh! It's so weird!
0:43:18 > 0:43:19Ah...
0:43:19 > 0:43:21Ugh!
0:43:21 > 0:43:23It's so clingy.
0:43:23 > 0:43:25Oh, my God!
0:43:30 > 0:43:32Oh...
0:43:32 > 0:43:34Ah...
0:43:39 > 0:43:41People have been doing what I'm doing
0:43:41 > 0:43:45way back to the time of the ancient Persians, although Lord knows
0:43:45 > 0:43:49what made them get their kit off and start to bathe in this stuff.
0:43:51 > 0:43:55I must admit, when I first saw it, it looked absolutely disgusting.
0:43:55 > 0:44:00The feeling of it being warm and clingy was horrible.
0:44:00 > 0:44:03But now, after five minutes,
0:44:03 > 0:44:06it still feels absolutely disgusting.
0:44:10 > 0:44:13Just as well this isn't its only use.
0:44:17 > 0:44:21You known, I think I can smell someone smoking,
0:44:21 > 0:44:23which is making me a bit jittery, because...
0:44:23 > 0:44:26well, because this is oil.
0:44:26 > 0:44:30I'm lying in a bath of petroleum.
0:44:30 > 0:44:31Ugh!
0:44:37 > 0:44:39ROARING
0:44:41 > 0:44:45Today, we've thought of a few more ways of using oil.
0:44:45 > 0:44:49It's the ultimate source of concentrated carbon energy.
0:44:50 > 0:44:54It's more energy-rich than coal, easier to transport,
0:44:54 > 0:44:57and it's got a million different uses.
0:45:06 > 0:45:10The use of oil is the pinnacle of our mastery of fire.
0:45:15 > 0:45:19Fittingly, the first country to benefit from the exploitation of oil
0:45:19 > 0:45:21was the home of naftalan...
0:45:22 > 0:45:24..Azerbaijan.
0:45:29 > 0:45:32For centuries, this thick, black, oily sludge
0:45:32 > 0:45:36was dug out of the ground here by hand, on a small-scale basis.
0:45:36 > 0:45:40But in the middle of the 19th century, demand for oil really took off,
0:45:40 > 0:45:44and what had been a cottage industry turned into this.
0:46:05 > 0:46:08Within 20 years, these fields were the site
0:46:08 > 0:46:11of the first great global oil boom.
0:46:11 > 0:46:12From across the world,
0:46:12 > 0:46:16entrepreneurs rushed to Azerbaijan to make their fortunes.
0:46:16 > 0:46:20Some succeeded so well that their names are almost legendary.
0:46:20 > 0:46:26The Shell oil company started life here, and the Nobel brothers of Nobel prize fame
0:46:26 > 0:46:30built their business empire on Azeri oil.
0:46:30 > 0:46:33This place oozed money!
0:46:42 > 0:46:44By the early 1900s,
0:46:44 > 0:46:48Baku, the capital of Azerbaijan,
0:46:48 > 0:46:51boasted more millionaires than anywhere else on Earth.
0:46:58 > 0:47:04But Azerbaijan really owed its sudden wealth to a fluke of geology.
0:47:14 > 0:47:19In the land of naftalan, oil happens to be exceptionally close to the surface.
0:47:23 > 0:47:28You can see how close at an unusual location in the south of the country.
0:47:33 > 0:47:37If you want to appreciate why this country was the site of the first great oil boom,
0:47:37 > 0:47:41you don't have to look any further than these curious mounds.
0:47:41 > 0:47:43It's not so much the mounds that's interesting,
0:47:43 > 0:47:45it's what's bubbling out of them - mud.
0:47:45 > 0:47:47But not just ordinary mud.
0:47:47 > 0:47:49Look what happens when I do this.
0:47:57 > 0:47:58D'oh!
0:48:01 > 0:48:04GLOOPING
0:48:06 > 0:48:11The reason it's flammable is that the mud is full of natural gas,
0:48:11 > 0:48:13which is formed along with the oil.
0:48:16 > 0:48:20You know, these things are like miniature volcanoes, really...
0:48:22 > 0:48:26..except that rather than hot, molten lava spewing out of the top,
0:48:26 > 0:48:28it's just mud.
0:48:28 > 0:48:33The thing is, you can dig into them, and you can see
0:48:33 > 0:48:37what the kind of plumbing is like inside, which is exactly what I'm doing now.
0:48:39 > 0:48:40GRUNTS
0:48:40 > 0:48:42Ah, now, look at this, look at this.
0:48:42 > 0:48:45You can see it in here.
0:48:45 > 0:48:50Mud is just bubbling up in this cavity, and then there's a little vent pipe
0:48:50 > 0:48:53that carries it up to the top, where it spews out.
0:48:53 > 0:48:55BUBBLING
0:48:57 > 0:48:59There were few places on Earth
0:48:59 > 0:49:02where it was easier to extract oil and gas than Azerbaijan.
0:49:02 > 0:49:04PLOPPING
0:49:06 > 0:49:10But by the start of the 20th century, demand for oil was rocketing,
0:49:10 > 0:49:14and new sources had to be found.
0:49:17 > 0:49:21Once again, the Earth's distant past would play a decisive role
0:49:21 > 0:49:23in meeting our needs.
0:49:27 > 0:49:33The big question is why a few lucky places ended up with huge oilfields,
0:49:33 > 0:49:34but others didn't.
0:49:34 > 0:49:38I don't think it's an exaggeration to say that the answer to that puzzle
0:49:38 > 0:49:42has shaped the global geopolitics of our age.
0:49:42 > 0:49:47It's probably the most powerful way that the Earth has influenced human history.
0:49:52 > 0:49:55After Azerbaijan faded from prominence,
0:49:55 > 0:49:59the Middle East became the key oil-producing region in the world.
0:50:01 > 0:50:06It owes this good fortune to a chain of events that began
0:50:06 > 0:50:08almost 300 million years ago.
0:50:12 > 0:50:14Back then, the two areas
0:50:14 > 0:50:19that would one day form most of the modern Middle East were separate,
0:50:19 > 0:50:20but they were on the move.
0:50:23 > 0:50:25Remarkably, as they moved,
0:50:25 > 0:50:30both areas spent much of the time submerged by shallow seas.
0:50:33 > 0:50:38So layer upon layer of dead sea creatures built up on the ocean floor.
0:50:40 > 0:50:43And when, periodically, the seas evaporated,
0:50:43 > 0:50:46layers of salt were also deposited.
0:50:52 > 0:50:54As the modern Middle East came together,
0:50:54 > 0:50:57these layers were buried deep inside the Earth,
0:50:57 > 0:51:02where the heat and pressure turned the dead sea creatures into oil.
0:51:11 > 0:51:14But the Earth played one final role in turning this area
0:51:14 > 0:51:19into the dominant oil-producing region in the world, and to see what it is...
0:51:21 > 0:51:25..I've come to an unusual mountain range in Iran.
0:51:30 > 0:51:35The drifting continents helped form the oil, but in most areas
0:51:35 > 0:51:37the oil was buried deep in the Earth.
0:51:43 > 0:51:45Too deep to be exploited.
0:51:47 > 0:51:50It needed to be brought closer to the surface,
0:51:50 > 0:51:54which is where salt returns to the story.
0:51:54 > 0:51:56As a geologist, I've been lucky enough
0:51:56 > 0:51:59to go to a lot of places and see a lot of rocks,
0:51:59 > 0:52:02but nothing really prepares you for what you find here.
0:52:02 > 0:52:08Cos here I am, walking in the scorching desert sun, looking down on a glacier.
0:52:08 > 0:52:12But that isn't made of ice - it's made of salt.
0:52:17 > 0:52:21This whole mountainside is covered in salt
0:52:21 > 0:52:24that's oozed upwards from deep inside the Earth...
0:52:26 > 0:52:30..the remains of a long lost ocean.
0:52:44 > 0:52:47You know, this is such a surreal landscape.
0:52:47 > 0:52:51What's hard to take is that virtually everything under my feet is moving.
0:52:51 > 0:52:53You can see that - look at this here.
0:52:53 > 0:52:56Look at these cracks that are opening up in the salt
0:52:56 > 0:52:59as it opens up and then closes again.
0:52:59 > 0:53:02And then also, here and there... Look, there's a bit.
0:53:03 > 0:53:09This was carried down the glacier by the salt from somewhere up there.
0:53:09 > 0:53:12I mean, this is exactly what ice does.
0:53:17 > 0:53:22Salt is similar to ice because it's soft and plastic, which is why it flows.
0:53:24 > 0:53:29On the Earth's surface, this means it can slide across the land like a glacier.
0:53:35 > 0:53:37But even more spectacular
0:53:37 > 0:53:43is the role it played underground in the formation of oil reserves.
0:53:48 > 0:53:51As the continents collided to form the Middle East,
0:53:51 > 0:53:57layers of salt and oil-rich rock strata began to buckle upwards.
0:53:57 > 0:54:02The salt made it much easier for the rock to bend, until eventually...
0:54:05 > 0:54:07..it cracked.
0:54:07 > 0:54:12Now the oil could flow upwards until it was trapped in a fold in the rock,
0:54:12 > 0:54:15kept in place by an impermeable layer above.
0:54:19 > 0:54:22The salt helped the rock slide easily,
0:54:22 > 0:54:27acting as a kind of lubricant, creating huge folds called anticlines,
0:54:27 > 0:54:29which were perfect for trapping oil.
0:54:29 > 0:54:34And where there are oil traps, there are generally oilfields.
0:54:35 > 0:54:39If you take a look at a map of the world's buried salt deposits,
0:54:39 > 0:54:42and overlay the major oilfields,
0:54:42 > 0:54:46it's easy to see why geologists searching for oil go looking for salt.
0:54:51 > 0:54:53It takes millions of years,
0:54:53 > 0:54:57and some pretty extraordinary geological events, to create
0:54:57 > 0:54:59an oil trap that we can exploit.
0:54:59 > 0:55:03So it's not surprising that only a few countries have oil beneath them.
0:55:03 > 0:55:09And when they find it, there's almost no limit to what they'll do
0:55:09 > 0:55:11to get it out of the ground.
0:55:13 > 0:55:17Nowhere symbolises this determination more than this town
0:55:17 > 0:55:20in the former Soviet Union.
0:55:24 > 0:55:28At first glance, this looks like your typical Eastern European town.
0:55:28 > 0:55:31You've got your standard-issue apartment blocks,
0:55:31 > 0:55:34and the architecture has got a real industrial feel to it.
0:55:40 > 0:55:42It was first started in the 1940s.
0:55:44 > 0:55:46It's got a football team...
0:55:49 > 0:55:51..and even a mosque.
0:55:54 > 0:55:57This place is called Oily Rocks,
0:55:57 > 0:56:00and over 2,000 people live and work there.
0:56:00 > 0:56:04If ever there was a monument to our obsession for oil, then this is it.
0:56:04 > 0:56:08Because what you don't see from the ground is that Oily Rocks
0:56:08 > 0:56:11was built in the middle of the Caspian Sea.
0:56:24 > 0:56:27It's 50 kilometres from dry land.
0:56:28 > 0:56:31Over the years, more than 600 oil wells
0:56:31 > 0:56:34have been drilled from these platforms.
0:56:35 > 0:56:41Today, Oily Rocks is still producing oil, but it's past its peak.
0:56:44 > 0:56:48And that about sums up our relationship with oil more generally.
0:56:53 > 0:56:57Today, we're burning it far faster than the planet can make it.
0:56:57 > 0:57:03It would take the Earth three million years to make enough oil
0:57:03 > 0:57:05for just one year of our consumption.
0:57:12 > 0:57:16We've reached a turning point in human history.
0:57:19 > 0:57:23Every major advance in human civilisation has been made possible
0:57:23 > 0:57:26by our ability to raid the Earth
0:57:26 > 0:57:29for ever more energy-rich forms of carbon.
0:57:31 > 0:57:36But our love affair with burning carbon-based fuel is coming to an end.
0:57:39 > 0:57:43Carbon itself has become the problem.
0:57:43 > 0:57:47Burning it produces greenhouse gases which are changing our climate.
0:57:50 > 0:57:55And that means if human civilisation is to continue to advance,
0:57:55 > 0:58:00we will have to break the link between progress and the burning of carbon.
0:58:11 > 0:58:15Next time, a very different planetary force...
0:58:15 > 0:58:16us.
0:58:16 > 0:58:19We are changing the surface of the planet more
0:58:19 > 0:58:23than all the forces of nature put together.
0:58:24 > 0:58:29But are we threatening the Earth's ability to support human civilisation?
0:58:56 > 0:58:59E-mail: subtitling@bbc.co.uk